Potassium titanate is a useful as a friction material for sliding members such as brake linings, disc pads, and clutch fading of braking devices in automobiles, railway vehicles, aircrafts, industrial machines, and the like. In particular, potassium hexatitanate (n is an integer of 6) has a tunnel crystal structure among potassium titanates represented by a general formula K2O.nTiO2 (n is an integer of 1 to 12), and a friction material containing the potassium hexatitanate fibers (fibrous particles) has been particularly known to reveal an excellent heat resistance and the like
Fibrous potassium titanate, however, has a poor formability due to its bulkiness and also it is hard to uniformly disperse the fibrous potassium titanate in the friction
material due to a low flowability, which means it is difficult to handle the fibrous potassium titanate.
Therefore, non-fibrous potassium titanate has been developed by a pulverization process of a calcined potassium hexatitanate with an impact crusher instead of fibrous potassium titanate (refer to Patent Document 1 (Japanese Patent Application Publication No. 2008-110918)) and, non-fibrous potassium titanate has been disclosed which is containing 0.7% to 1.3% of a powder having a diameter of 3 μm or smaller, a length of 5 μm or larger, a ratio of the length to the diameter (an aspect ratio) of 3 or larger when the powder is observed under an electron microscope as the non-fibrous potassium titanate.
Potassium titanate has a strong adhesivity and thus a technical problem has been arised in that potassium titanate has a tendency of an adherence to an inner surface wall of a raw materials mixer or a pad molding machine in case of producing the friction material and the yield is likely to fall as a result.